Fuses blow based on amperage(resistance) not voltage(current).
That just hurt my brain, Amperage is a measurement of Current, Resistance and Voltage are seperate units, resistance is measured in Ohms and voltage in... well... volts. What I think you meant was that Fuses blow based on temperature (heating of a thin wire element) which is caused by the resistance. Resistance is dependent on both Voltage and Current (V=I*R [I is current, R is resistance, V is voltage, rearrange the equation and R=V/I) but resistance increases with heat. Overcurrent the fuse (25 amps or more) and it will heat up exponentially untill the wire element breaks contact and breaks the circuit. If your gun is pulling more than 25 amps continuous, something is wrong, either you have a wire thats been nicked and is occasionally grounding out to something metal, or the motor is shot, or you are running a very bleh battery with a motor that isnt getting the voltage/current it needs or something mechanical is causing your electricals to demand more current than the amperage is capable of.
Replacing with a 25A fuse is a MUST, any higher and you no longer have the safety mechanism, and any lower you wont be able to use the gun for long without breaking another fuse.